The focus of this proposal is to identify molecular targets of tsetse fly reproductive physiology for the development of novel biological control strategies for the prevention of disease transmission. Tsetse are the vectors of trypanosomiasis in both humans and animals in sub-saharan Africa creating major health and economic problems. There are no vaccines to control disease in the mammalian host and only a single and highly toxic drug is available for treatment of late stage infections. Vector control methods, such as trapping and insecticide spraying, are effective in reducing fly challenge. Vector reduction methods are especially effective due to the low fly population numbers resulting from tsetse's slow reproductive rate. Tsetse has an unusual reproductive biology as they only develop one offspring at a time and give birth to a fully developed larva. Reproduction in tsetse is also unique in that it requires the presence of obligate mutualist symbiotic bacteria. Nutrients for the developing intrauterine larva are supplied entirely by the mother. Nutrients are transferred from the mother to offspring by milk secretions generated in a specialized accessory gland called the milk gland. Disruption of the flow of nutrients into the developing larva, or the elimination of symbiotic bacteria both result in loss of host fecundity. The application has three goals. The first goal focuses on the transfer of lipids from the fat body tissue to the milk gland and its regulation. It will identify and characterize the conserved peptide hormone/receptor system (adipokinetic hormone) responsible for regulating lipid mobilization in insects as well as the system responsible for the physical movement of lipids through the hemolymph (lipophorin/lipophorin receptor). The second goal focuses on the protein components of the milk secretion. It will identify novel milk proteins in silico and characterize the promoter and regulatory regions to understand the transcription factors responsible for milk gland/pregnancy specific expression patterns. The third goal focuses on the indispensable role of symbiotic bacteria in host reproductive processes. It will characterize the factors symbionts provide to facilitate host fecundity, analyze the expression patterns of host reproduction associated genes in symbiont-cured sterile flies. Collectively, the proposed studies will identify key elements required for tsetse reproductive processes. These elements stand to provide targets for tsetse specific vector control strategies for use in the prevention of trypanosomiasis.